1. Field of the Invention
The invention relates to a releasable turnstile lock.
2. Description of the Prior Art
Such releasable turnstile locks are known both with vertical rotational axles as well as such which are inclined against the horizontal. In both embodiments the drive is designed in such a way that the star-type rotating body always moves over an angle of 180.degree. at each step.
This leads to the disadvantage, however, that in such a releasable turnstile lock the passage can never be released for a period exceeding the duration of a step of the startype rotating body, which would be required during the occurrence of an emergency or a panic. It is therefore necessary in such releasable turnstile locks that the second delimitation of the passage can be respectively displaced or pivoted away in order to allow a larger number of persons to pass rapidly.
Such an arrangement is only possible, however, if the required space was provided for already during the layout of a building secured by such a turnstile lock.
In known such turnstile locks it has also been proposed to provide the arms projecting from the star-type rotating body with a joint that can be unlatched. In the event of an alarm the joint of the arm in the blocking position is unlatched, whereby the joint having an axis extending substantially horizontal and perpendicular to the longitudinal axis of the respective arm. As a result of the unlatching of the joint, the arm can suspend in a substantially downward vertical manner, with the unlatching occurring by an electromagnet or also by overpressing a catch.
This leads to the disadvantage, however, that the arm can be brought even by involuntary contact to an oscillating movement which is directed transversally to the passage and obstructs the same, e.g. by touching with wider cut clothing such as skirts. As a result, the following persons, which due to an alarm will follow at very small intervals, can be endangered to a very considerable extent, thus leading in particular to a high danger of falling.
Moreover, joints that can be locked require a considerable amount of design and production effort and it is necessary in such known turnstile locks to return manually the arms of the star-type rotating bodies again to their operational position after each initiation of an alarm.
Moreover, three-arm releasable turnstile locks are known in which the arms are mutually connected with the star-type rotating body via elastically deformable coupling elements.
Such releasable turnstile locks lead to the disadvantage that the passage cannot be freed up completely and arms can get entangled during the oscillating movement during a panic, which could lead to a serious endangerment of such persons. Moreover, such a turnstile lock requires continuous monitoring, as otherwise unauthorised passage of the turnstile lock could otherwise not be recognised.